The present disclosure is generally directed to toner compositions, and more specifically, to toner compositions including coated carrier components. In embodiments, the coated carrier particles can be prepared with polymeric components utilizing dry powder processes.
Electrophotographic printing utilizes toner particles which may be produced by a variety of processes. One such process includes an emulsion aggregation (“EA”) process that forms toner particles in which surfactants are used in forming a latex emulsion. See, for example, U.S. Pat. No. 6,120,967, the disclosure of which is hereby incorporated by reference in its entirety, as one example of such a process.
Combinations of amorphous and crystalline polyesters may be used in the EA process. This resin combination may provide toners with high gloss and relatively low-melting point characteristics (sometimes referred to as low-melt, ultra low melt, or ULM), which allows for more energy efficient and faster printing. The use of additives with EA toner particles may be important in realizing optimal toner performance, especially in the area of charging, where crystalline polyesters on the particle surface can lead to poor A-zone charge.
The sensitivity of toner charge to relative humidity (RH) may result in a major loss in toner concentration (TC) latitude, in that the TC must be controlled more tightly to enable good development and background. High triboelectric charge at low RH limits development, while low triboelectric charge at high RH produces background, and both high and low triboelectric charge result in poor print quality.
In addition, recent trends to ultra-low melt (ULM) toner are even more sensitive to relative humidity due to the use of polyester resins which may include crystalline polyesters. Also, with the move to even smaller toner particles, the triboelectric charge and TC latitude is reduced, and can no longer accommodate a large charge difference with environment. For example, for toners with particles of 4 microns in size or less, there is much less latitude between development at low RH and background at high RH. Thus, for these toners, excellent triboelectric charge/RH sensitivity is very important.
There remains a continual need for improving the use of additives in the formation of toners.